Bionic desk and chair for correcting posture

ABSTRACT

A bionic and posture-correcting desk and chair, including a desk and chair or stool, which are separate or combined. The bottoms of desk legs are connected with a footrest, and a chair back is connected between supports of the chair back. At the upper and lower parts of the desk and chair are disposed with a posture-correcting device and a mechanism for fixing the posture-correcting device. The posture-correcting device allows users to maintain the correct “forward sitting position” and “backward sitting position” or a sitting position therebetween all the time. The bionic and posture-correcting desk and chair ensures sitting positions which are comfortable and unlikely to cause fatigue and are easily adjusted.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of International Patent Application No. PCT/CN2010/075952 with an international filing date of Aug. 12, 2010, designating the United States, now pending, and further claims priority benefits to Chinese Patent Application No. 200920166775.0 filed Aug. 12, 2009. The contents of all of the aforementioned applications, including any intervening amendments thereto, are incorporated herein by reference.

CORRESPONDENCE ADDRESS

Inquiries from the public to applicants or assignees concerning this document should be directed to: MATTHIAS SCHOLL P.C., ATTN.: DR. MATTHIAS SCHOLL ESQ., 14781 MEMORIAL DRIVE, SUITE 1319, HOUSTON, Tex. 77079.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a bionic and posture-correcting desk and chair, and more particularly to a bionic and posture-correcting desk and chair for primary or middle school students.

2. Description of the Related Art

From the perspective of the hygienics, “forward sitting position” is defined if a user's upper body gravity is right on or in the front of the ischiatic tuberosity, where the balance is maintained by the back muscles and thighs. “Backward sitting position” is defined if a user's upper body gravity is behind the ischiatic tuberosity, where the back must be against the backrest. It is apparent that the forward sitting position is likely to cause fatigue while the backward sitting position is not. However, nowadays students are fond of using the forward sitting position to study by bending over the desks. If students do not care about their sitting positions for study or writing, they are more likely to suffer from fatigue, short-sight and hunchback. The “forward sitting position” and the “backward sitting position” should be used as the two basic positions and also they should be changeable with each other.

Conventional posture-correcting desks and chairs have the following disadvantages: 1. The height of the desks and chairs has to be adjusted by adjusting the upper and lower desk/chair legs, and afterwards the desks and chairs have to be fixed by screws. After the desks and chairs are adjusted, they are not suitable for users with different height. Furthermore, it is complicated to adjust the desks and chairs and they are less durable if they are adjusted too much; 2. The distance between the desks and chairs has to be adjusted by adjusting the adjustable tube underneath and afterwards the desks and chairs have to be fixed by screws. After the desks and chairs are adjusted, they are not suitable for users with different weight. It is not easy for users to change the correct forward and backward sitting positions and the position in between and it is not convenient for users to enter and come out; 3. The rear edge of the desk is not disposed with the device to prevent short sight and hunchback, or the device fails to meet the requirements after being mounted; and 4. It is not easy to adjust the inclination degree of the desktop and the bookrack according to the requirements. In addition, the desk and chair legs, bookrack and chair back have not completely fulfilled the functions. There are other problems that have not been paid much attention, for example, it is not easy to tidy the desks and chairs, the noises made when moving the desks and chairs, it is not easy for cleaning, the space (i.e. desk box) for holding books is too small and the desks and chair are difficult to be moved.

SUMMARY OF THE INVENTION

In view of the above-described problems, it is one objective of the invention to provide a bionic and posture-correcting desk and chair. It allows users to maintain the correct “forward sitting position” and “backward sitting position” or a sitting position therebetween all the time, and meanwhile the sitting positions which are comfortable and unlikely to cause fatigue can be easily adjusted or changed.

To achieve the above objective, in accordance with the invention, there is provided a bionic and posture-correcting desk and chair, comprising a separate or combined desk and chair or stool, the bottom of desk legs being connected with a footrest and a chair back being connected between supports of the chair back, wherein at the upper and lower parts of the desk and chair are disposed with a posture-correcting device and a mechanism for fixing the posture-correcting device; the posture-correcting device is replaceable at will and allows users to maintain the correct “forward sitting position” and “backward sitting position” or a sitting position therebetween all the time.

In a class of this embodiment, the posture-correcting device and the mechanism for fixing the posture-correcting device are a lifting mechanism disposed between a desktop and a bookrack.

In a class of this embodiment, the lifting mechanism comprises a vertical slot disposed at the relative inner sides of the desk's left and right front legs. The relative inner sides of the upper ends of the left and right supports are attached by a vertical plate. The supports connect the vertical plate and its two ends are moveable up and down the vertical slot and the inner legs. The upper ends of the two supports are moveably connected with the front end of the desktop. The middle of the left and right sides of the vertical plate projects upwards and passes through left and right long-strip apertures on the desktop to be parallel with the desktop. On the boss portion is disposed with 1-2bookrack support holes. Inside the support holes is disposed with a moveable pin that fits with the recess on a support tube of the bookrack. The moveable pin has a bow-shaped leaf spring or an aperture on the wall of the support hole. Inside the aperture is disposed with a smaller boss. The rear end of the boss is connected with a column, whose rear end is against a spring. At the rear bottom of the desktop is disposed with a position adjusting tooth that fits with an edge angle of the upper end of the desk box.

In a class of this embodiment, the lifting mechanism comprises a rear bottom of the desktop moveably connected with the rear upper end of the desk box. The rear front end of the desktop is moveably connected with the vertical plate. The middle portion of the left and right sides of the vertical plate projects upwards and passes through the long-strip apertures on the desktop to be parallel with the desktop. On the boss portion is disposed with 1-2 bookrack support holes. Inside the support hole is disposed with a moveable pin that fits with a support tube of the bookrack. From the top to the bottom of the desk boxes are respectively disposed with a control groove inclining backwards. The control groove and column underneath are sheathed together. The rear of the vertical plate is moveably connected with a support pillar. The lower left and right edge angles of the support pillar fit with the arc-shaped teeth of a desk box baseplate.

In a class of this embodiment, the lifting mechanism comprises a rear bottom of the desktop moveably connected with the rear upper end of the desk box. The middle portion, from the front end of the desktop, is disposed with a long-strip aperture. Inside the aperture is provided with a moveable bracket, whose opposite left and right ends extend with a shaft and whose middle portion is connected by front and rear plates. The left and right sides of the moveable bracket are respectively disposed with a bookrack support hole. In the middle of the moveable bracket is disposed with an adjustable tube hole. At the bottom of the front end of the desk box is moveably connected with an adjustable tube that is sheathed with an adjustable tubular pile. The upper end of the adjustable tube extends to be parallel with the desktop through the adjustable tube hole on the moveable bracket. The upper end of a connecting rod in the adjustable tube is connected with a button and the lower end thereof is connected with an adjustable pin. At the connection point between the moveable bracket and the adjustable tube is disposed with a vertical slot and a cross rod is used to connect the moveable bracket and the adjustable tube as a whole.

In a class of this embodiment, on the desk footrest or the chair footrest provided with wheels is disposed with a lock mechanism, which is used to keep the desk and chair steady relative to the ground.

In a class of this embodiment, the desk footrest or the chair footrest is disposed with a foot button as the lock mechanism, whose bottom is connected with foot block by a spring.

In a class of this embodiment, for the posture-correcting device and the mechanism for fixing the posture-correcting device, at least one footrest is disposed at the place where the height-unadjustable desk and chair legs are flatly placed. The footrest is directly or indirectly placed on the ground or the track or covered in the desk layer cover to float above the connecting bracket.

In a class of this embodiment, the footrest is disposed on a height-adjustable desk and chair having signal left and right legs. The width of the footrest is the width of the desk legs and the footrest is fixed on the desk legs. Alternatively, the footrest is disposed on a height-unadjustable desk and fixed on the desk legs. The rear ends of the chair beams are moveably connected with the lower ends of the chair back supports. Between the lower portions of the chair beams and chair bases are connected with lower chair legs. The lower ends of the upper chair legs are inserted in the upper ends of the lower chair legs on the chair beams and fixed. The desk and chair legs comprise upper legs and lower legs and the upper ends of the two lower legs are connected together as a whole. The lower ends of the two upper legs that are connected under the desk box and the chair beam are respectively inserted in the upper ends of the lower legs and fixed. The rear end of the chair beam is moveably connected with the lower end of the chair back support. The opposite outer sides of the front ends of chair armrests are respectively connected with an armrest plate. The armrest plate is moveably connected with a moveable tube outwards. The movable tube comprises an external tube and an internal tube. The front end of the internal tube is moveably connected with the armrest plate and the rear end of the external tube is moveably connected with the chair back supports. The front end and the bottom of the external tube are reversely disposed with a spring bolt. The spring bolt fits with the positional adjustment holes at the front lower portion of the internal tube. The rear section of the internal tube is disposed with an aperture. The aperture moveably cooperates with an adjustable slot under the rear section of the external tube. The chair back is moveable back and forth or fixed. In addition, if the chair has four legs disposed at four sides, the chair having the chair base disposed between the left and right chair legs can be placed on the desk footrest having a leg cover opening and a leg cover aperture.

In a class of this embodiment, the desk and chair legs are disposed with layer covers. The width of the layer cover is the length between the front and rear legs of the desk and chair and the length of the layer cover is the length between the left and right legs. The layer cover is connected with the gap of one layer or multiple layers of at least two strips. The outer sides of the left and right ends of the transversal layer cover, or the front and rear or one end of the longitudinal layer cover are separately connected with a baffle. The strips are directly connected with the legs or the vertical plate having the same width as the two legs. The left and right sides of the vertical plate cover the other two sides of the legs to form a recess/square tube/circular tube layer cover, which is fixed to the legs by the bolt (spring clamp) via the positional adjustment holes or moveably covered on the legs. A connecting plate is used to connect the two ends of the vertical plate. One end of the vertical plate is disposed with an aperture that fits with the corresponding boss of the footrest. A flat square is disposed under the chair or the footrest. Between the flat square and the vertical plate is disposed with a layer cover. The layer cover, the long-strip aperture or pin head are sheathed together.

Advantages of the invention are summarized below: 1. According to the bionic principle, the lower end of the single-column lower adjustable pillar, similar to the desk backrest sternal plate, extends to the lower part of the abdomen and the bottom of the desk box (desk box baseplate) from the chest to the desk edge. The fixed connection between the lower end of the lower adjustable pillar and the desk edge is changed to the moveable connection. The upper adjustable plate between the desk backrest sternal plate and the ventral plate is inserted in a transversal gap of the adjustable plate cover or the adjustable cover of the mounting plate. The lower adjustable plate moveably connected with the lower end of the sternal/ventral plate is directly or indirectly moveably connected with the desktop lifting mechanism and the bookrack lifting mechanism to make the desk and chair as a whole. The desk or the chair is disposed with a footrest. A chair back support adjustment mechanism and a chair back adjustment mechanism are disposed on the chair including the layer covers, tracks, desk and chair seats and foot button. The problem that students study by bending over the desks is solved by using such structure. If the user places his feet hardly on the footrest, the sternal/ventral plate and the chair back are against the chest, abdomen, waist and back. The user is clamped in the middle. He can bend over or lean behind at will. The desktop can be flat or inclined. The bookrack can be lifted with the desktop and remains the optimal distance and angle with eyes, therefore a reasonable space will be formed between the head, eyes, neck, chest, abdomen, waist, back, buttocks, elbows, legs, feet and the desk and chair. Users will always be at the correct “forward sitting position” or “backward sitting position” or any position in between. In addition, the position can be changed at will and students will not easily fatigue. It saves large amount of time for teaching and study; 2. The distance between the desk and the chair can be adjusted at will. Although it is the distance that is adjusted and controlled between the desk and the chair, the amount of inclination for forward and backward movement of the waist, back, chest and abdomen are indirectly controlled. Furthermore, the chair back and a sternal/ventral plate are supported and moveably connected. It is helpful to keep the waist, back, chest and abdomen straight, to allow the feet to place flat to be as wide as the shoulder. Users can easily meet the requirement for study with correct sitting positions. The space between the desk and the chair can be adjusted to be wide or narrow and users can bend over or lean behind. They are suitable for the nature of students; 3. The height of the desk and chair can be easily adjusted, especially with the application of the layer covers. Screwdrivers and wrenches are not required. It overcomes the drawbacks that tall users need to bend over and short users cannot reach. The set of desk and chair is suitable for users whether you are young or old. Only one set of the desk and chair is enough for a primary student, who can still use in high school. For a class, the desk and chair can be tailored for different students with different height. After using the desk and chair, the students will be at the same height; 4. By using the desk and chair provided by the invention is good for tidiness. The noises when moving the desk and chair is low. The chair box provided by the invention can hold more books. The desk and chair are moveable; it is easy for students to clean the floor; and 5. The bionic and posture-correcting desk and chair provided by the invention is applicable not only for families but schools. The effects are immediate. The structure is simple and it is easy to be popularized.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in further detail below with reference to the embodiments and attached drawings.

FIG. 1 is a structural representation of a desk in accordance with example 1 of the invention;

FIG. 2 is a structural representation of a supporting chair of FIG. 1;

FIG. 3 is a structural representation of the desk in accordance with example 2 of the invention;

FIG. 4 is a structural representation of the supporting chair of FIG. 3;

FIG. 5 is a structural representation of the desk in accordance with example 3 of the invention;

FIG. 6 is a structural representation of the supporting chair of FIG. 5;

FIG. 7 is a sectional view of a moveable tube of FIG. 5;

FIG. 8 is a structural representation of the desk in accordance with example 4 of the invention;

FIG. 9 is a structural representation of the supporting chair of FIG. 8;

FIG. 10 is a front view of another chair;

FIG. 11 is a side view of the chair of FIG. 10;

FIG. 12 is a schematic diagram of the chair of FIG. 10 in use;

FIG. 13 is a structural representation of the desk in accordance with example 5 of the invention;

FIG. 14 is a schematic diagram of another connecting method of the desk and chair of FIG. 13;

FIG. 15 is a schematic diagram of another connecting method of the desk and chair of FIG. 13;

FIG. 16 is a structural representation of the desk in accordance with example 6 of the invention;

FIG. 17 is a structural representation of the supporting chair of FIG. 16;

FIG. 18 is a front sectional view of a lock mechanism of FIG. 16;

FIG. 19 is a structural representation of the desk in accordance with example 7 of the invention;

FIG. 20 is a structural representation of the supporting chair of FIG. 19;

FIG. 21 is a top view of the side edge at the other end of the lock long-strip plate of FIG. 19 being engaged with the side edge of one end of the connecting plate;

FIG. 22 is a top view of the side edge of the acute angle plate of the lock being engaged with the side edge of one end of the connecting plate;

FIG. 23 is a side view of another connecting method of the desk and chair of FIG. 13;

FIG. 24 is a side view of another connecting method of the desk and chair of FIG. 14;

FIG. 25 is a side view of a footrest with upper and lower plates of the invention;

FIG. 26 is a side view of a lever type footrest of the invention;

FIG. 27 is a layout view of a desk and chair frame of the invention;

FIG. 28 is another layout view of the desk and chair frame of the invention;

FIG. 29 is a third layout view of the desk and chair frame of the invention;

FIG. 30 is a side view of the desk and chair in accordance with example 8 of the invention;

FIG. 31 is a structural representation of the desk and chair in accordance with example 9 of the invention;

FIG. 32 is a front view of a desktop lifting mechanism of the invention when lifting the desktop;

FIG. 33 is a side view of FIG. 32;

FIG. 34 is a rear view of another desktop lifting mechanism of the invention;

FIG. 35 is a side view of FIG. 34;

FIG. 36 is a side view of FIG. 34 when the desktop is being lifted;

FIG. 37 is a top view of a desk box baseplate of FIG. 34;

FIG. 38 is a rear view of a third desktop lifting mechanism of the invention;

FIG. 39 is a top view of the desktop of FIG. 38;

FIG. 40 is a top view of a moveable pin of FIG. 38;

FIG. 41 is a rear view of FIG. 40;

FIG. 42 is a side sectional view of a desk backrest of the invention being mounted on the desktop which is placed horizontally;

FIG. 43 is a side sectional view of the desk backrest and the desktop lifting mechanism of the invention being mounted on the desktop which is placed horizontally;

FIG. 44 is a partially side sectional view of the desk backrest and the desktop lifting mechanism of the invention being mounted on a moveable connection part of the desk;

FIG. 45 is a top view of a vertical clamp plate and a lifting plate of the desktop lifting mechanism of the invention being mounted on the desk box baseplate;

FIG. 46 is a top view of the vertical clamp plate and the lifting plate of the desktop lifting mechanism of the invention being mounted at the left and right desk box side plates; and

FIG. 47 is a bottom view of a spring adjustment mechanism of the desktop lifting mechanism being mounted at the bottom of the desk box.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As shown in FIGS. 1-47, a bionic and posture-correcting desk and chair, in accordance with the invention, comprises a separate or combined desk and chair or stool, the bottom of desk legs are connected with a footrest and a chair back 17 is connected between its supports 18, in which at the upper and lower parts of the desk and chair and/or between the desk and chair (between desk legs and chair legs) are disposed with a posture-correcting device and a mechanism for fixing the posture-correcting device. The posture-correcting device allows users to maintain the correct “forward sitting position” and “backward sitting position” or the sitting position in between at all times, and meanwhile the device is replaceable at will.

As shown in FIGS. 32-33, between the desktop and the bookrack 109 is disposed with a lifting mechanism for the bookrack 109. The lifting mechanism comprises a vertical slot that is disposed at the relative inner sides of the desk's left and right front legs (the front and the rear are determined by the user who occupies the chair). The relative inner sides of the upper ends of the left and right supports 122 are attached by a vertical plate 25. The supports 122 connecting the vertical plate 25 and its two ends are moveable up and down the vertical slot and the inner legs. The upper ends of the two supports 122 are moveably connected with the front end of the desktop. The ⅓ of the left and right sides of the vertical plate 25 projects upwards and passes through left and right long-strip apertures on the desktop to be parallel with the desktop. On the boss portion is disposed with 1-2 bookrack support holes. Inside the support holes is disposed with a moveable pin that fits with the recess on a support tube of the bookrack 109. The moveable pin has a bow-shaped leaf spring or an aperture on the wall of the support hole. Inside the aperture is disposed with a smaller boss. The rear end of the boss is connected with a column, whose rear end is against a spring. At the rear bottom of the desktop is disposed with a position adjusting tooth 33 that fits with an edge angle of the upper end of the desk box. When the desktop is lifted, the two supports 122 and the bookrack support tube 112 extend upwards accordingly while the lower end of a book placing board 115 extends forwards. The desktop will be clamped on the edge angle at the rear upper end of the desk box by the position adjusting tooth 33. When the desktop is lowered, the two supports will contract downwards, the desktop is against a side plate 16 of the desk box and the lower end of the book placing board retreats. Whether the desktop is flat or inclined, the support tube 112 always remains vertical and the book placing board 115 always remains the optimal distance and angle with eyes.

As shown in FIGS. 34-37, with respect to the lifting mechanism, the rear bottom of the desktop is moveably connected with the rear upper end of the desk box. The rear front end of the desktop is moveably connected with the vertical plate 25 having the same length and width as a front plate 15 of the desk box. The middle portion of the left and right sides of the vertical plate 25 projects upwards and passes through the long-strip apertures on the desktop to be parallel with the desktop. On the boss portion is disposed with 1-2 bookrack support holes. Inside the support holes is disposed with a moveable pin that fits with a support tube of the bookrack. At the front inner sides of the two side plates 16 of the desk box are respectively disposed with a control groove 118 inclining backwards from top to bottom. The lower ends (both ends of the relative direction) of the left and right sides of the vertical plate 25 extend with columns 37. The control grooves 118 and columns 37 are sheathed together. The middle lower portion of the rear left and right sides of the vertical plate 25 is moveably connected with a support pillar 84, whose lower left and right edge angles fit with the arc-shaped teeth 133 of a desk box baseplate 13. When the desktop is lifted, the edge angle of the support pillar 84 moves from left or right on the arc-shaped teeth 133 and holds the desktop. When the desktop is lowered, the support pillar 84 has to be lifted by hands and moved to one side with the desktop. However, whether the desktop is lifted or lowered, the vertical plate 25 always remains vertical. The columns 37 at the two ends of the vertical plate 25 always move up and down in the control groove 118. The advantages are as above.

As shown in FIGS. 38-41, with respect to the lifting mechanism, the rear bottom of the desktop is moveably connected with the rear upper end of the desk box. The middle portion, approximately 1-2 cm from the front end of the desktop, is disposed with a long-strip aperture. Inside the aperture is provided with a moveable bracket 128, whose opposite left and right ends extend with a shaft 125 and whose middle portion is connected by front and rear plates. The left and right sides of the moveable bracket 128 are respectively disposed with a bookrack support hole 114. In the middle of the moveable bracket is disposed with an adjustable tube hole 117. In the middle of the bottom left and right of the inner front end of the desk box is moveably connected with an adjustable tube that is sheathed with an adjustable tubular pile 147. The upper end of the adjustable tube extends to be parallel with the desktop through the adjustable tube hole 117 on the moveable bracket 128. The upper end of a connecting rod in the adjustable tube is connected with a button 54 and the lower end thereof is connected with an adjustable pin. At the connection point between the moveable bracket 128 and the adjustable tube is disposed with a vertical slot 127 and a cross rod 129 is used to connect the moveable bracket 128 and the adjustable tube as a whole. The button 54 is used to lift or lower the desktop. The advantages are as above.

As shown in FIGS. 1-31, with respect to the posture-correcting device of the desk and chair and a mechanism for fixing the posture-correcting device, on a height-fixed desk and chair is provided with a maximum height and space 38 for high school students or tall individuals. At the distance that desk moves close to the chair to meet the requirement for correct sitting position, a person sits on the chair having the corresponding height, the back is against the chair back 17, the head, chest and abdomen are against the desk backrest 21, the elbows are placed on the desktop having the corresponding height and on an elbow plate 6, and one or more footrests are disposed at the place where the feet are placed. From the lower ends to the upper ends of the desk/chair legs are connected with at least one footrest. The footrest is directly or indirectly placed on the ground or on a track 30 or covered in a desk and chair cover to float above a connecting bracket 71. The footrest of the invention is not an ordinary one and it is either wider or narrower. Certainly, if the footrest is wider, it is easy for feet to place on. But in fact it is not the key point. Because when people are clamped and supported or bend over or lean behind, if the chair is fixed and the desk is moveable, or the desk is fixed and the chair is moveable, the forward or backward tension would be imposed on both the desk and the chair, making the desk or chair to move or incline, especially the ones with wheels. In order for students to study in a comfortable way or not to suffer from fatigue, it is necessary to keep a reasonable distance between the desk and the chair. The feet must step on the footrest hardly to keep the desk and the chair as a whole. In this way, although it is the distance that is adjusted and controlled between the desk and the chair, the amount of inclination for forward and backward movement of the waist, back, chest and abdomen are indirectly controlled. Furthermore, the chair back 17 and a sternal/ventral plate 178 are supported and moveably connected. It is helpful to keep the waist, back, chest and abdomen straight. It allows users to maintain the correct “forward sitting position” and “backward sitting position” or the sitting position in between at all times. A user can also change the sitting position at will, place the feet flat, keep the feet as wide as the shoulder and allow eyes to maintain an optimal distance and angle with the book placing board 115. Therefore, under such state, the footrest becomes a connecting or stop device between the desk and the chair and it forms an integral part of the posture-correcting device.

The footrest comprises a desk footrest 20 and a chair footrest 201. As shown in FIGS. 1-2, the desk footrest 20 is disposed on a height-adjustable desk and chair having single left and right legs. The desk footrest 20 has the same width as the desk and is fixed to the desk legs by bolts 34 via positional adjustment holes 32. As shown in FIGS. 3-4, the desk footrest 20 is disposed on a height-unadjustable desk and fixed to the desk legs by the bolts 34 via the positional adjustment holes 32. The rear ends of chair beams 19 are connected with the lower ends of the chair back supports 18. Between the lower portions of the chair beams 19 and chair bases 9 are connected with lower chair legs. The lower ends of the upper chair legs are inserted in upper ends of the lower chair legs on the chair beam 19 and fixed by the bolts 34 via the positional adjustment holes 32. As shown in FIGS. 5-6, the desk and chair legs comprise upper legs and lower legs and the upper ends of the two lower legs are connected together as a whole. The lower ends of the two upper legs that are connected under the desk box and the chair beam 19 are respectively inserted in the upper ends of the lower legs and fixed by the bolts 34 via the positional adjustment holes 32. The rear ends of the chair beams 19 are moveably connected with the lower ends of the chair back supports 18. The opposite outer sides of the front ends of chair armrests 45 are respectively connected with an armrest plate 56. The armrest plate 56 is moveably connected with a moveable tube 44 outwards. As shown in FIG. 7, the movable tube 44 comprises an external tube 161 and an internal tube 61. The front end of the internal tube 61 is moveably connected with the armrest plate 56 and the rear end of the external tube 161 is moveably connected with the chair back supports 18. The front end and the bottom of the external tube 161 are reversely disposed with a spring bolt 134. The spring bolt 134 fits with the positional adjustment holes 32 at the front lower portion of the internal tube 61. The rear section of the internal tube 61 is disposed with an aperture. The aperture moveably cooperates with an adjustable slot 94 under the rear section of the external tube 161 by the bolt 34. The chair back 17 is moveable back and forth or fixed. In addition, if the chair has four legs disposed at four sides, the chair having the chair base 9 disposed between the left and right chair legs can be placed on the desk footrest 20 having a leg cover opening 85 and a leg cover aperture. In this way, the chair can be stably placed without touching the ground.

As shown in FIGS. 8-12, 19-24, 27, 29-31, the lower portion of the desk legs and the upper portion of the chair legs are disposed with a layer cover. The layer cover comprises a transversal layer cover 221 and a longitudinal layer cover 22. The width of the layer cover equals to the length between the inner sides (including the legs) of the front and rear legs of the desk or chair. The length of the layer cover equals to the length between the left and right legs (between the inner sides of the left and right legs). The layer cover is connected with the gap of one layer or multiple layers of at least two strips 23. The outer sides of the left and right ends of the transversal layer cover 221, or the front and rear or one end of the longitudinal layer cover 22 are separately connected with a baffle 24. The strips 23 are directly connected with the legs or the vertical plate 25 having the same width as the two legs. The left and right sides of the vertical plate 25 cover the other two sides of the legs to form a recess/square tube/circular tube layer cover, which is fixed to the legs by the bolt (spring clamp) via the positional adjustment holes 32 or moveably covered on the legs. A connecting plate 26 is used to connect the two ends (the bottom strips 23 or chair box side plate 16) of the vertical plate 25. One end of the vertical plate 25 is disposed with an aperture that fits with the corresponding boss of the footrest. A flat square 182 is disposed under the chair or the footrest. Between the flat square 182 and the vertical plate 25 is disposed with a layer cover. The layer cover and the long-strip aperture or pin head are sheathed together.

As shown in FIGS. 13-24 and 28-29, the desk footrest or the chair footrest with wheels is disposed with a lock mechanism, which ensures that the desk or the chair is fixed relative to the ground. On a height-fixed desk and chair is provided with a maximum height and space 38 for high school students or tall individuals. At the distance that desk moves close to the chair to meet the requirement for correct sitting position, a person sits on the chair having the corresponding height, the back is against the chair back 17, the head, chest and abdomen are against the desk backrest 21, the elbows are placed on the desktop having the corresponding height or on the elbow plate 6. A spring type footrest is disposed at the place where the feet are placed flat.

As shown in FIGS. 13-14 and 19, under the four angles of the footrest are vertically disposed with columns 37, which are inserted in corresponding resilient support holes 132 of a footrest seat 58. The resilient support holes 132 are circular tubes 162 that are sheathed with springs 35 (externally or internally). The underside of the footrest is against by springs 35 which are sheathed higher than the circular tubes 162. After the footrest 20 is under pressure, the lower ends of the columns 37 fall to the ground and the lower ends of the columns 37 are sheathed with cap nuts. As shown in FIGS. 23-24 and 28-29, the columns 37 of the footrest 20 whose four angles are sheathed with bolts 34 are inserted in corresponding desk/chair bases 9. The upper ends of the two chair bases 9 have the same size as the springs 35 and the lower ends are inserted in the apertures (big at the upper portion and small at the lower portion) having the same size as the bolts 34. The upper ends of the springs 35 are against the bolts 34 and the lower ends are on the platform between the upper section and the lower section. As shown in FIG. 15, the footrest seat 58 is disposed on the two front chair legs. The two angles (above the columns 37) of the chair footrest 201 adjacent to one end of the chair are respectively disposed with an aperture and connected with a tube, which are fixed to the two front chair legs with the footrest seat 58.

As an improvement, if the footrest is used as the footrest seat 58 and place the spring type footrest in a rectangular square (the length and width are defined by feet) in the middle of the footrest seat 58, the footrest under pressure will be parallel with the footrest seat 58. As shown in FIGS. 16-18, the middle portion of the desk footrest 20 is disposed with a foot button 173. The lower portion of the foot button 173 is connected with a foot block 174 by the springs 35. When the desk is unused, the springs 35 act on the foot block 174 to leave the ground to make the desk move. When the desk is in use, the springs 35 act on the foot block 174 to be tightly against the ground because feet are placed on foot button 173. Alternatively, the above structure can also be used for chair footrest 201.

As an improvement, the layer covers and the spring type footrest can be combined together to be disposed in the desk and chair. As shown in FIGS. 23-24 and 29, the layer covers are placed in a layer box 68, which is connected with the upper portion of the spring type footrest. The spring type footrest is disposed on the chair base 9, which extends ½ or half of the chair length. The front and rear bottoms of the chair base 9 are respectively disposed with wheels 11 to fit with the desk that is either fixed to the ground or disposed on the connecting bracket 71. The layer cover between the left and right chair legs matches with the chair and the desk is applicable to a plurality of chairs. With respect to the layer box 68, the layer cover is mounted from the left and right sides of the footrest and the baffle is mounted at the rear end of the layer cover. As an improvement, similar to FIGS. 27-28 and 30, the layer box 68 can be disposed on the connecting bracket 71 or the track 30. Use a hinge to connect the rear upper end of the layer box 68 to the front of the chair front legs of the connecting bracket 71. The front two upper ends of the layer box 68 extend to the left and right sides with a butt plate. The butt plate is either on the connecting bracket 71 or the track 30. The chair fits with the desk that is fixed on the connecting bracket 71. As shown in FIGS. 27 and 30, the chair is fixed at the rear of the connecting bracket 71. The desk whose front and rear legs are disposed with wheels 11 and desk base-tops 10 is placed on the connecting bracket 71 or the track 30. The relative outer lower ends of the desk legs are connected with the upper section of a flat bar 72. The relative inner lower ends of the lower section of the flat bar 72 are connected with the longitudinal layer cover 22 and float under the desk legs. The desk is moveable back and forth along the track 30.

As shown in FIGS. 19-22, the lower portions of the desk legs are moveably disposed with a transversal layer cover 221. The underside of the bottom strip 23 of the transversal layer cover 221 is connected with the upper end of the columns 37 of the spring type footrest. The spring type footrest uses the two desk bases 9 whose front and rear sides are disposed with wheels 11 as the footrest seat 58. The desk footrest 20 that fits with the transversal layer cover 221 is disposed in a moveable cover 76. The width of the moveable cover 76 equals to the width between the front and rear sides (including the front and rear desk legs) of the transversal layer cover 221 and the length of the moveable cover equals to the length between the left and right desk legs. The inward recess at the opposite sides of the left and right moveable cover 76 is formed by vertical plates, upper/lower strips and front/rear baffles. The front of the recess is disposed with a convex plate 78 at the left and right legs. The convex plate is then equipped with a spring. Between the left and right desk legs, the rear of the recess is sheathed with the desk footrest 20 whose width equals to the length of the desk leg. The shaft passes through the aperture, the spring and the convex plate 78 that are in the recess of the desk footrest 20 to fix the desk footrest to the center of the front and rear baffles of the recess. The upper and lower portions of the front section of the recess are attached by the connecting plate 26 as a whole. Because the desk footrest 20 is extendable and the desk can move close to the chair, the leg cover opening 85 is not required. The middle of the two desk bases 9 and the connecting plate 26 in the middle of the desk bases 9 are disposed with a lock 79. An aperture 232 in the middle of the left and right sides of the long-strip plate 82 of the lock 79 is moveably connected with the corresponding portion of the connecting plate 26 and the aperture 232 is used as the centre of circle to the bottom of the strips 23 at the middle of the front and rear desk legs as an arc edge 81. From the aperture 232 on a long-strip plate 82 to one side of the chair at one end of the arc edge 81 is connected with an acute angle plate that is shorter from the aperture 232 to the arc edge 81. The other end of the acute angel plate (including the centre of circle to the long-strip plate 82) having the same length as the acute angle plate has a side edge facing downwards) (90°). As shown in FIG. 21, when a user kicks the side edge of the other end of the long-strip plate 82 by feet to make it engage with the side of one end of the connecting plate 26, the arc edge 81 at the two ends of the long-strip plate 82 is just under the left and right strips 23, and the lower end of the column 37 under pressure cannot reach to the ground. As shown in FIG. 22, when a user kicks the side edge of the acute angle plate by feet to make it engage with the side of one end of the connecting plate 26, the arc edge 81 at the two ends of the long-strip plate 82 moves to the front and rear inner sides of the left and right strips 23, and the lower end of the columns 37 under pressure can reach to the ground. The upper portion of the chair legs are further equipped with the longitudinal layer cover 22 and the flat square 182. Furthermore, it is possible to make apertures at the front and rear of the bottom strip 23 to the chair. Then use a reversed T-shaped pin to fasten from bottom to top and rotate 90 degree to place the pin on a reversed hook at the L-shaped opening under the strip 23.

With respect to the posture-correcting device and the mechanism for fixing the posture-correcting device, on the height-unadjustable desk and chair is disposed with a maximum height and space 38 for high school students or high individuals. At the distance that desk moves close to the chair to meet the requirement for correct sitting position, a person sits on the chair having the corresponding height, the back is against the chair back 17, the head, chest and abdomen are against the desk backrest 21, the elbows are placed on the desktop having the corresponding height or on an elbow plate 6, and one or more footrests are disposed at the place where the feet are placed. As shown in FIG. 25, in the ¼ point from the lower end of the desk and chair to the maximum height is moveably connected with the chair footrest 201. The width of the chair footrest 201 is the width of the desk and chair and the length of the chair footrest is the maximum length when the desk and chair are separate. At that point, the footrest can be placed on the ground or on a desk support plate 60 or on the connecting bracket 71 or can move in the lay cover. The footrest and the support plate 60 can be adjusted up and down by the bolts 34 of the positional adjustment holes 32. The footrest is covered in the layer cover. The positional adjustment holes 32 fit with each layer distance of the layer covers. The chair footrest 201 on the chair legs fits with the layers of the longitudinal layer cover 22 at the same level of the lower portion of the desk legs. The chair surface fit with the layer covers on the chair legs. The front and rear of the two desk bases 9 are disposed with the wheels 11.

With respect to the posture-correcting device and the mechanism for fixing the posture-correcting device, on the height-unadjustable desk and chair is disposed with a maximum height and space 38 for high school students or tall individuals. At the distance that desk moves close to the chair to meet the requirement for correct sitting position, a person sits on the chair having the corresponding height, the back is against the chair back 17, the head, chest and abdomen are against the desk backrest 21, the elbows are placed on the desktop having the corresponding height or on an elbow plate 6, and one or more footrests are disposed at the place where the feet are placed. As shown in FIG. 26, on the footrest seat 58 in the ¼ section from one end to the maximum height of the chair is moveably connected with the chair footrest 201, whose the end close to the chair is lower and the end far from the chair is a little higher. The width of the chair footrest 201 equals to the width of the desk and chair and the length of the chair footrest equals to the maximum length when the desk and chair are separate. At that point, the footrest on the desk support plate 60 or the butt plate projected from two sides of the chair footrest 201 is moveable along the connecting bracket 71, or the chair footrest 201 (one section of the front end folds downwards or the foot block 174 is provided) is against the ground. The resistance point of the lever provides resilient support or is the support pillar. The support pillar supports the resilient footrest. The footrest seat 58 and the support plate 60 are adjustable up and down by the bolts 34 of the positional adjustment holes 32.

As shown in FIGS. 1-31, the footrest or the support plate 60 is disposed with the leg cover opening 85 or the leg cover hole, or under the footrest or the support plate 60 is disposed with a leg space 87. The width of the leg cover opening 85 of the desk footrest 20 close to the chair is a little more than the width of the left and right chair front legs or equal to the width between the left and right front legs or the chair box 12. The front and rear of the desk come close to the maximum of one or two vertical rectangle or a transversal rectangular opening. The leg cover opening 85 fits with the leg cover hole. The leg cover hole which is at the front (or slightly at the rear side) of the desk footrest 20 fits with the leg cover opening 85 at the rear of the desk footrest. The width of the leg cover hole equals to the width of the leg cover opening 85 and the length is slightly longer than the length between the front and rear of the front leg. The shape is one or two square, rectangle or circle or a transversal rectangular hole or opening. The leg space 87 is at the bottom of the desk footrest 20. The height of the leg space is slightly higher than or as high as the chair base 9 and the width is slightly wider than the chair base 9 or comprises the two chair bases 9. The length of the leg space is in the space of two vertical cuboids or a big transversal flat cuboid of the desk footrest 20 when the chair base 9 is sheathed into the desk footrest 20 to the limit. The leg cover opening 85 and the leg cover hole on the support plate 60 or the leg space 87 under the support plate are similar to the desk footrest 20. In the invention, in order for the feet to be placed on the footrest, the footrest is required to be wider. As shown in FIGS. 1 and 16, if the chair has single left and right legs, the footrest 20 is required to have the leg space 87 to be covered in the chair base 9. As shown in FIG. 31, in order for the desk and chair legs to be sheathed together, the desk footrest 20 is disposed with left and right leg cover openings 85. FIGS. 5 and 8 show a long leg cover opening 85.

As shown in FIGS. 1-31 and 42-47, the desk is disposed with the desk backrest 21 (i.e. the bionic and posture-correcting backrest for study). The desk backrest 21 comprises a bracket body at the rear of the desk where a mounting bracket 90 is disposed. When a user sits on the chair behind the desk, the frame (from the chest and abdomen to the desk edge, from the chin to the lower part of the abdomen and above the thighs) is disposed with an adjustable adjustment element, which allows the user to maintain the correct “forward sitting position” and “backward sitting position” or a position in between. The bracket body comprises at least one adjustable tubular pile 147 and a pectoral/ventral plate 178. The pectoral/ventral plate 178 is moveably connected with an upper adjustable plate 98. Inside the adjustable tubular pile 147 is sheathed with a chin adjustment element, which is used to adjust the height of the chinrest 177. The mounting bracket 21 is on the desk or on the base plate 91 at the upper end of the desk box. The lower end of the single-column lower adjustable pillar, similar to the desk backrest 21, extends to the lower part of the abdomen and the bottom of the desk box (desk box baseplate 13) from the chest to the desk edge. The upper part of the thighs is disposed with the pectoral/ventral plate 178, which is used to fix the lower end of the lower adjustable pillar to the mounting bracket 90. In the invention, the fixed connection is changed to the moveable connection. The sternal plate and the ventral plate of the mounting bracket 90 is moveably connected with the upper adjustable plate 98, which is inserted in a transversal gap 67 of the adjustable plate cover or the adjustable cover of the mounting plate 90. The pectoral/ventral plate 178 is indirectly moveably connected with a chair back 17 to make the desk and chair form a whole part. The lower end of the pectoral/ventral plate 178 is connected with an adjustable plate 99, which is directly or indirectly moveably connected with an adjustable baseplate 89, a desktop lifting mechanism or a bookrack lifting mechanism. The bracket body is disposed with a ventral plate adjustment mechanism and a bracket folding mechanism. When the feet are placed hardly on the footrest, the user sitting between the pectoral/ventral plate 178 and the chair back 17 is clamped or supported by the pectoral/ventral plate 178 and the chair back 17. The users can bend over or lean behind at will. The desktop can be flat or inclined, the bookrack 109 can be lifted or descended with the desktop, and a book placing board 115 can remain the optimal distance and angle with eyes. The desk backrest 21 used in the invention can also be replaced by the bionic and posture-correcting backrest for study described in the patent 2009201681014.

As show in FIGS. 43-47, the lower rear end of the desktop is moveably connected with the rear upper end of the desk. The desk having the desk backrest 21 is disposed with the desktop lifting mechanism. As shown in FIG. 45, the desktop lifting mechanism is placed in the middle (from top to bottom or from left to right) of the desk box baseplate 13 and the two sides of the desktop lifting mechanism are fixed with vertical clamp plate 101. The vertical clamp plates are used to clamp a pumpkin-seed-shaped lifting plate 102 of the desk box baseplate 13. As shown in FIG. 46, the desk box side plates 16 whose left and right lifting plates 102 are disposed at the inner sides of the desk box and which are used as the vertical clamp plate 101 are clamped by the relative inner sides of the vertical clamp plate 101. As shown in FIG. 43, the rear upper portion of the vertical clamp plate 101 is moveably connected with the corresponding part (with the bolts 34) of the lifting plate 102. As shown in FIGS. 43-47, the rear top end (slightly inside) of the lifting plate 102 is moveably connected with the front end (with the holes 32 and bolts 34) of a secondary connecting plate 103. The rear of the secondary connecting plate 103 is placed on a raised edge 104 at the rear edge of the adjustable baseplate 89 and the raised edge extends out of the adjustable baseplate. The lower adjustable plate 99 that is moveably connected with the lower end (slightly at the upper position) of the sternal/ventral plate 178 is moveably connected with a step 105 and a flat plate 106 on the secondary connecting plate 103 as well as a magnet 57 that is disposed in the middle of the raised edge 104 of the adjustable baseplate 89. The front ends of the left and right lifting plates 102 are connected with 1-2 connecting plate 26. As shown in FIGS. 43-44 and 47, the bottom of the desk box baseplate 13 is reversely disposed with a spring adjustment element. A reversed hanger plate 107 of the spring adjustment element is in the middle of the left and right front ends. The reversed hanger plate is moveably connected with the front end of a longitudinal plate 261 and 1-2 columns 83 stand on the rear front end or slightly inner position of the reversed hanger plate. The spring 35 on the column 83 supports the desk box baseplate 13 and is against the longitudinal plate 261. The column 83 passes through the hole 32 on the desk box baseplate 13 (or the adjustable baseplate 89). The upper end of the column is sheathed with a hanger plate whose diameter is larger than that of the column 83 and is moveably hanged on the desk box baseplate 13 to be parallel with the upper portion of the adjustable baseplate 89. Alternatively the longitudinal plate 261 is placed on the reversed hook at the bottom of the column. At the corresponding place of the secondary connecting plate 103 is disposed with an aperture to fit with the column 83. In addition, the upper arc of the lifting plate 102 is moveably connected with the magnet that is disposed at the bottom of the desktop.

As shown in FIGS. 1-47, the desk equipped with the desktop lifting mechanism is moveably connected with the bookrack lifting mechanism. As shown in FIGS. 43-46, on a bookrack seat 110 at the front end of the lifting plate 102 is moveably connected with 1-2 frame tubes 111 in the transversal direction. The upper end of the frame tube 111 vertically passes through and extends over the top of the desktop. As shown in FIG. 1, the bookrack 109 is composed of the book placing board 115 and 1-2 support tubes 112 that are moveably connected at the rear of the bookrack. The book placing board 115 is disposed with a book holding groove 116 and the lower end of the book placing board is connected with a book baffle. The support tube 112 of the bookrack 109 and the frame tube 111 are moveably sheathed together. The frame tube 111 on the desktop is sheathed with a moveable pad or the lower end of the support tube 112 is connected with a circular pad. The arc-shaped angle at the lower end of the book placing board 115 attracts with the forward and backward magnets on the desktop. The bookrack 109 can be flat or inclined along with the desktop lifting mechanism and the book placing board 115 always remains the optimal distance and angle with eyes. The left and right sides of the book placing board 115 indirectly attracts with the opened book by magnet. Furthermore, for the purpose of storage, it is possible to mount upper and lower moveable connecting mechanisms at the front end of the lifting plate 102 or on 1-2 bookrack seats 110 of the connecting plate 26. One end of the lower moveable connecting mechanism is moveably connected with the lifting plate 102 (connecting plate 26) in the longitudinal direction. The frame tube 111 can be taken out from the desktop and inclinedly against a bracket or the connecting plate 26 of the desk box front plate 15. The other end of the upper moveable connecting mechanism is moveably connected with the lower end of the frame tube 111 in the transversal direction and is rotatable back and forth. The frame tube 111 can vertically extends over the top of the desktop. The book placing board 115 and the support tube 112 are disposed with a clamp and a storage slot.

As shown in FIGS. 1-4 and 16, the desktop is disposed with the desktop lifting mechanism, which is at the upper and lower sides in the transversal direction of the length of a lifting adjustment plate 126. One side is parallel and the other side is inclined. On the lifting adjustment plate 126 is disposed with the adjustable slot 94, which is parallel with the parallel edge of the lifting adjustment plate 126. The lifting adjustment plate 126 is fixed on the desk box side plate 16 by bolts 34 via the adjustable slot 94. Furthermore, the adjustable slot 94 parallel to the lifting adjustment plate 126 can be transversally disposed at the corresponding position of the desk box side plate 16. In the middle of the transversal adjustable slot 94 is disposed with a vertical slot. The lifting adjustment plate 126 is sheathed on the desk box side plate 16 by bolts 34 via the adjustable slot 94.

As shown in FIGS. 23-31, the chair is on the ground. The front of the desk is disposed with the wheel 11 and the rear of the desk is disposed with the desk base-top 10. Alternatively, the front and rear of the desk are both disposed with the wheels 11, or the desk is fixed on the ground, or the front and rear of the chair are both disposed with the wheels 11. The chair is fixed on the ground at the inner side of the two parallel tracks 30 or close to the inner side of the two tracks 30 or on the tracks 30. The desk is on the two tracks 30 or close to the outer side of the tracks 30 or on the ground at the outer side of the tracks 30. The front of the desk is disposed with the wheel 11 and the rear of the desk is disposed with the desk base-top 10, or the front and rear of the desk are both disposed with the wheels 11, or the desk is fixed on the ground at the outer side of the two parallel tracks 30 or close to the outer side of the tracks 30 or on the tracks 30. The chair is on the two tracks 30 or close to the inner side of the track 30 or on the ground at the inner side of the track 30. The chair is disposed on the track 30 of a desk/chair holder 130 or of a double-layer desk/chair holder 131 or disposed on the connecting plate 26. The desk is disposed on the track 30 at the front of the chair, the front of the desk is disposed with the wheel 11, and the rear of the desk is disposed with the desk base-top 10 or both the front and rear of the desk are disposed with the wheels 11. Alternatively, the desk is disposed on the track 30 of the desk/chair holder 130 or of the double-layer desk/chair holder 131 or disposed on the connecting plate 26. The chair is disposed on the track 30 at the rear of the desk and both the front and rear of the chair are disposed with the wheels 11. The desk/chair holder 130 is a frame composed of one or more pairs of longitudinal tracks 30 and two or more transversal connecting plates 26, or the double-layer desk/chair holder 131 is formed by connecting the upper and lower frames. Under the desk/chair holder 130 and the double-layer desk/chair holder 131 are disposed with support legs 136 or the wheels 11. The desk/chair holder 130 and the double-layer desk/chair holder 131 can be disposed with one or more sets or one or more rows of desks and chairs in the longitudinal and transversal directions, respectively. The desks and chairs are not against one another. As shown in FIGS. 1, 3 and 8, the wheels 11 at the front end of the desk base 9 are parallel with the desk base 9 and the ground. The front end of the desk base 9 is in the shape of an arc. Similar to FIGS. 27 and 30, the lower sections of the chair legs can be omitted. It is only required to mount the upper sections of the chair legs on the desk/chair holder 130, or the inner sides of the tracks 30 and the connecting plate 26. For the purpose of study, the desks and chairs provided by the invention remain a certain distance. As the desks and chairs are frequently moved, they are disposed with the wheels 11, the tracks 30, the desk/chair holder 130 or the double-layer desk/chair holder 131. For easy cleaning, the lower sections of the chair legs are not required.

One end of the desk/chair holder 130 of the bionic and posture-correcting desk and chair is disposed with a frame head, or the driver seat is combined with the chair as a whole.

As shown in FIGS. 1-31, the chair back support 18 is disposed with the chair back adjustment mechanism. As to the chair back adjustment mechanism, the chair back 17 is moveably connected with the sternal/ventral plate 178 of the desk backrest 21 in an indirect way. The chair back 17 is moveably connected with the upper section of the chair back support 18 by bolts 34 via the positional adjustment holes 32 on the chair back support 18. As shown in FIGS. 5-6, the chair back 17 is disposed with a pillow backrest 135. The pillow backrest 135 is covered by a pillow 137 and provides support for the waist. The lower end of the pillow backrest 135 can be inserted in the chair back support 18 or a storage tube 138 at the rear of the chair legs. Alternatively, the bookcase can be added on the desktop and the chair box 12 can be added under the chair.

On the chair back support 18 is disposed with the chair back support adjustment mechanism. The chair back support adjustment mechanism divides the left and right chair back supports 18 into upper and lower chair back supports. The upper chair back support is covered in the lower chair back support. The relative inner sides of the upper ends of the two upper chair back supports are moveably connected with the chair back 17. The lower sections of the two upper chair back supports are fixed with a resilient adjustment pin. The resilient adjustment pin is a resilient strip (piece) and is in a bended shape (or the circular bended shape). The end of the bended strip is disposed with 1-2 projected pins, passing through the aperture on the inner wall of the upper chair back support and fit with the positional adjustment holes of the lower chair back support. The two ends of the chair back 17 are moveably connected with the upper chair back support and can be adjusted up and down in the lower chair back support.

As shown in FIGS. 1-31 and 42, when a user sits on the chair, he withdraws his feet, uses his hands to pull or push the desk or chair to the appropriate distance, allows his waist to lean against the chair back 17 and chest/abdomen lean against the sternal/ventral plate 178, uses his feet to stamp on the footrest hardly to allow the desk to be securely connected with the chair as a whole. Place the two elbows on the desktop or on the elbow plate 6, and place the chin on the chin pad of the desk backrest. When the user bend over or lean behind, the desk backrest 21 will move with the chair back 17 and the user will be “clamped” in the middle. It allows the user to maintain the correct “forward sitting position” and “backward sitting position” or the sitting position in between at all times, and meanwhile the sitting positions which are comfortable and unlikely to cause fatigue can be easily adjusted or changed. In addition, the book placing board 115 is adjustable back and forth to maintain the optimal distance and angle with eyes. At this point, the lower adjustable plate 99 is on the adjustable baseplate 89 to move back and forth. When a user leans forwards, the chin is on the chin pad and the neck becomes shorter. When the user lean backwards, the neck become longer. Consequently, the user is required to press the adjustment button on the desk backrest 21 when to change the sitting position. In that case, the adjustable support can be extended and the chin can be placed on the chin pad.

As shown in FIGS. 43-47, when the desktop is flat, the user is “clamped” in the middle of the desk backrest 21 and the chair back 17 to maintain the correct “forward sitting position” and “backward sitting position” or the sitting position in between at all times, and meanwhile the sitting positions can be easily adjusted or changed. The book placing board 115 can be pulled or pushed forwards or backwards and is moveable up and down the frame tube 111 together with the support tube 112. The book placing board 115 maintain the optimal distance and angle with eyes. At this point, the lower adjustable plate 99 is moveable along the step 105 of the secondary connecting plate 103. When the desk backrest 21 leans forwards to the maximum limit of the correct “forward sitting position”, the lower adjustable plate 99 will fall from the step 105 to the flat plate 106 underneath. The end of the lower adjustable plate 99 will be against the front of the secondary connecting plate 103 at the front of the flat plate 106. At this point, it is the fixed and correct “forward sitting position”. If the user uses the study position with the inclined desktop, when the user uses his elbows to press the elbow plate 6 and uses his abdomen to act on the sternal/ventral plate 178, the secondary connecting plate 103 will move forwards under the effect of the adjustable baseplate 89. The end of the secondary connecting plate 103 will be naturally placed in the inner side of the raised edge 104 of the adjustable baseplate 89 and against with each other. The front end of the lifting plate 102 will be gradually raised up and stop after it pushes the desktop to get the required inclined state. The support tube 112 is moveably connected with the frame tube 111 and goes up with front end of the lifting plate 102. The lower end of the book placing board 115 moves forwards on the desktop and remains the optimal distance and angle with eyes. The front end of the lower adjustable plate 99 is moveable along the flat plate 106 and the raised edge 104. At this point, the user can lean forwards or backwards with the desk backrest 21 and the chair back 17, and maintain the correct “forward sitting position” and “backward sitting position” or the sitting position in between at all times, and meanwhile the sitting positions which are comfortable and unlikely to cause fatigue can be easily adjusted or changed. It should be noted that during the process when the secondary connecting plate 103 moves towards on the desktop under the effect of the lower adjustable plate 99, the user can use his elbows to press the elbow plate 6 and uses his abdomen to push the sternal/ventral plate 178 to maintain balance. The desktop can be easily made with different inclined angles for correct “backward sitting position”. If the user intends to use the study position with the flat desktop again, he can use his elbows to press the elbow plate 6 and use his abdomen to act on the sternal/ventral plate 178, and at the same time use one feet that is on the desk footrest 20 to kick the rear of the lower longitudinal plate 261 to enable the column 83 to push the secondary connecting plate 103 to the top of the raised edge 104 of the adjustable baseplate 89. Afterwards, when the users uses his elbows to press the elbow plate 6 to allow the desktop to slowly drop, he uses the chest to act on the sternal/ventral plate 178 of the desk backrest 21 to allow the desk backrest 21 to be back to the position for correct “forward sitting position”. The desktop will be back to the flat position. The support tube 112 is sheathed with the frame tube 111 and perpendicularly drops with the desktop. The lower end of the book placing board 115 moves backwards and remains the optimal distance and angle with eyes. If the user intends to lean forwards or backwards, he can use his feet to kick the rear of the longitudinal plate 261 to allow the column 83 to pass through the aperture on the secondary connecting plate 103 and push the lower adjustable plate 99 from the flat plate 106 to the step 105 of the secondary connecting plate 103 under the condition that the end of the lower adjustable plate 99 is moveable on the step 105 of the secondary connecting plate 103. In this way, the user will always be at the correct “forward sitting position” or “backward sitting position” or any position in between, and meanwhile the sitting positions can be changed at will. If the user intends to change the distance between the desk and the chair or have a rest, what he needs to do is to raise his feet and push or pull the desk or chair once. 

1. A bionic and posture-correcting desk and chair, comprising a separate from one another or combined with one another desk and chair or stool, the bottom of desk legs being connected with a footrest, and a chair back (17) being connected between supports (18) of the chair back, wherein at the upper and lower parts of the desk and chair are disposed with a posture-correcting device and a mechanism for fixing the posture-correcting device; the posture-correcting device allows users to maintain the correct “forward sitting position” and “backward sitting position” or a sitting position therebetween all the time; and the posture-correcting device is replaceable at will.
 2. The bionic and posture-correcting desk and chair of claim 1, wherein the posture-correcting device and the mechanism for fixing the posture-correcting device are a lifting mechanism disposed between a desktop and a bookrack.
 3. The bionic and posture-correcting desk and chair of claim 2, wherein the lifting mechanism comprises a vertical slot disposed at the relative inner sides of the desk's left and right front legs; the relative inner sides of the upper ends of the left and right supports (122) are attached by a vertical plate (25); the supports (122) connect the vertical plate (25) and its two ends are moveable up and down the vertical slot (25) and the inner legs; the upper ends of the two supports (122) are moveably connected with the front end of the desktop; the middle of the left and right sides of the vertical plate (25) projects upwards and passes through left and right long-strip apertures on the desktop to be parallel with the desktop; on the boss portion is disposed with 1-2 bookrack support holes; inside the support holes is disposed with a moveable pin that fits with the recess on a support tube of the bookrack (109); the moveable pin has a bow-shaped leaf spring or an aperture on the wall of the support hole; inside the aperture is disposed with a smaller boss; and the rear end of the boss is connected with a column, whose rear end is against a spring; at the rear bottom of the desktop is disposed with a position adjusting tooth (33) that fits with an edge angle of the upper end of the desk box.
 4. The bionic and posture-correcting desk and chair of claim 2, wherein the lifting mechanism comprises a rear bottom of the desktop moveably connected with the rear upper end of the desk box; the rear front end of the desktop is moveably connected with the vertical plate (25); the middle portion of the left and right sides of the vertical plate (25) projects upwards and passes through the long-strip apertures on the desktop to be parallel with the desktop; on the boss portion is disposed with 1-2 bookrack support holes; inside the support hole is disposed with a moveable pin that fits with a support tube of the bookrack; from the top to the bottom of the desk boxes are respectively disposed with a control groove (118) inclining backwards; the control groove (118) and column (37) underneath are sheathed together; the rear of the vertical plate (25) is moveably connected with a support pillar (84); and the lower left and right edge angles of the support pillar (84) fit with the arc-shaped teeth (133) of a desk box baseplate (13).
 5. The bionic and posture-correcting desk and chair of claim 2, wherein the lifting mechanism comprises a rear bottom of the desktop moveably connected with the rear upper end of the desk box; the middle portion, from the front end of the desktop, is disposed with a long-strip aperture; inside the aperture is provided with a moveable bracket (128), whose opposite left and right ends extend with a shaft and whose middle portion is connected by front and rear plates; the left and right sides of the moveable bracket (128) are respectively disposed with a bookrack support hole (114); in the middle of the moveable bracket is disposed with an adjustable tube hole (117); at the bottom of the front end of the desk box is moveably connected with an adjustable tube (147) that is sheathed with an adjustable tubular pile; the upper end of the adjustable tube extends to be parallel with the desktop through the adjustable tube hole (117) on the moveable bracket (128); and the upper end of a connecting rod in the adjustable tube is connected with a button (54) and the lower end thereof is connected with an adjustable pin; at the connection point between the moveable bracket (128) and the adjustable tube is disposed with a vertical slot (127) and a cross rod (129) is used to connect the moveable bracket and the adjustable tube as a whole.
 6. The bionic and posture-correcting desk and chair of claim 1, wherein for the posture-correcting device and the mechanism for fixing the posture-correcting device, a height-fixed desk and chair is provided with a maximum height and space (38); at least one footrest is disposed at the place where a user's legs are flatly placed; and the footrest is directly or indirectly placed on the ground or the track (30) or covered in the desk layer cover (22) to float above the connecting bracket (71).
 7. The bionic and posture-correcting desk and chair of claim 6, wherein the footrest (20) is disposed on a height-adjustable desk and chair having signal left and right legs; the width of the footrest (20) is the width of the desk legs and the footrest is fixed on the desk legs; alternatively, the footrest (20) is disposed on a height-unadjustable desk and fixed on the desk legs; the rear ends of the chair beams (19) are moveably connected with the lower ends of the chair back supports (18); between the lower portions of the chair beams (19) and chair bases (9) are connected with lower chair legs; the lower ends of the upper chair legs are inserted in the upper ends of the lower chair legs on the chair beams (19) and fixed; the desk and chair legs comprise upper legs and lower legs and the upper ends of the two lower legs are connected together as a whole; the lower ends of the two upper legs that are connected under the desk box and the chair beam (19) are respectively inserted in the upper ends of the lower legs and fixed; the rear end of the chair beam (19) is moveably connected with the lower end of the chair back support (18); the opposite outer sides of the front ends of chair armrests (45) are respectively connected with an armrest plate (56); the armrest plate (56) is moveably connected with a moveable tube (44) outwards; the movable tube (44) comprises an external tube (161) and an internal tube (61); the front end of the internal tube (61) is moveably connected with the armrest plate (56) and the rear end of the external tube (161) is moveably connected with the chair back supports (18); the front end and the bottom of the external tube (161) are reversely disposed with a spring bolt (134); the spring bolt (134) fits with the positional adjustment holes (32) at the front lower portion of the internal tube (61); the rear section of the internal tube (61) is disposed with an aperture; the aperture moveably cooperates with an adjustable slot (94) under the rear section of the external tube (161); the chair back is moveable back and forth or fixed; and in addition, if the chair has four legs disposed at four sides, the chair having the chair base disposed between the left and right chair legs can be placed on the desk footrest (20) having a leg cover opening (85) and a leg cover aperture.
 8. The bionic and posture-correcting desk and chair of claim 7, wherein the desk and chair legs are disposed with layer covers; the width of the layer cover is the length between the front and rear legs of the desk and chair and the length of the layer cover is the length between the left and right legs; the layer cover is connected with the gap of one layer or multiple layers of at least two strips (23); the outer sides of the left and right ends of the transversal layer cover (221), or the front and rear or one end of the longitudinal layer cover (22) are separately connected with a baffle (24); the strips (23) are directly connected with the legs or the vertical plate (25) having the same width as the two legs; the left and right sides of the vertical plate (25) cover the other two sides of the legs to form a recess/square tube/circular tube layer cover, which is fixed to the legs by the bolt (spring clamp) via the positional adjustment holes or moveably covered on the legs; a connecting plate (26) is used to connect the two ends of the vertical plate (25); one end of the vertical plate (25) is disposed with an aperture that fits with the corresponding boss of the footrest; a flat square (182) is disposed under the chair or the footrest; between the flat square (182) and the vertical plate (25) is disposed with a layer cover; and the layer cover, the long-strip aperture or pin head are sheathed together.
 9. The bionic and posture-correcting desk and chair of claim 1, wherein the desk footrest (20) or the chair footrest (201) with wheels is disposed with a lock mechanism, which ensures that the desk or the chair is fixed relative to the ground; a spring type footrest is disposed at the place where the feet are placed flat.
 10. The bionic and posture-correcting desk and chair of claim 9, wherein for the spring type footrest, under the four angles of the footrest are vertically disposed with columns (37), which are inserted in corresponding resilient support holes (132) of a footrest seat (58); the resilient support holes (132) are circular tubes (162) that are sheathed with springs (35) (externally or internally); the underside of the footrest is against by springs (35) which are sheathed higher than the circular tubes (162); after the footrest (20) is under pressure, the lower ends of the columns (37) fall to the ground and the lower ends of the columns (37) are sheathed with cap nuts; the columns (37) of the footrest (20) whose four angles are sheathed with bolts (34) are inserted in corresponding desk/chair bases (9); the upper ends of the two chair bases (9) have the same size as the springs (35) and the lower ends are inserted in the apertures (big at the upper portion and small at the lower portion) having the same size as the bolts (34); the upper ends of the springs (35) are against the bolts (34) and the lower ends are on the platform between the upper section and the lower section; the footrest seat (58) is disposed on the two front chair legs; the two angles (above the columns (37)) of the chair footrest (201) adjacent to one end of the chair are respectively disposed with an aperture and connected with a tube, which are fixed to the two front chair legs with the footrest seat (58); if the footrest is used as the footrest seat (58) and place the spring type footrest in a rectangular square in the middle of the footrest seat (58), the footrest under pressure will be parallel with the footrest seat (58); the middle portion of the desk footrest (20) is disposed with a foot button (173); the lower portion of the foot button (173) is connected with a foot block (174) by the springs (35); when the desk is unused, the springs (35) act on the foot block (174) to leave the ground to make the desk move; for the lock mechanism, the layer covers are placed in a layer box (68), which is connected with the upper portion of the spring type footrest; the spring type footrest is disposed on the chair base (9), which extends ½ or half of the chair length; the front and rear bottoms of the chair base (9) are respectively disposed with wheels (11) to fit with the desk that is either fixed to the ground or disposed on the connecting bracket (71); the layer cover between the left and right chair legs matches with the chair and the desk is applicable to a plurality of chairs; with respect to the layer box (68), the layer cover is mounted from the left and right sides of the footrest and the baffle is mounted at the rear end of the layer cover; the layer box (68) can be disposed on the connecting bracket (71) or the track (30); use a hinge to connect the rear upper end of the layer box (68) to the front of the chair front legs of the connecting bracket (71); the front two upper ends of the layer box (68) extend to the left and right sides with a butt plate; the butt plate is either on the connecting bracket (71) or the track (30); the chair fits with the desk that is fixed on the connecting bracket (71); the chair is fixed at the rear of the connecting bracket (71); the desk whose front and rear legs are disposed with wheels (11) and desk base-tops (10) is placed on the connecting bracket (71) or the track (30); the relative outer lower ends of the desk legs are connected with the upper section of a flat bar (72); the relative inner lower ends of the lower section of the flat bar (72) are connected with the longitudinal layer cover (22) and float under the desk legs; and the desk is moveable back and forth along the track (30).
 11. The bionic and posture-correcting desk and chair of claim 9, wherein for the posture-correcting device and the mechanism for fixing the posture-correcting device, a height-fixed desk and chair is provided with a maximum height and space (38); the lower portions of the desk legs are moveably disposed with a transversal layer cover (221); the underside of the bottom strip (23) of the transversal layer cover (221) is connected with the upper end of the columns (37) of the spring type footrest; the spring type footrest uses the two desk bases (9) whose front and rear sides are disposed with wheels (11) as the footrest seat (58); the desk footrest (20) that fits with the transversal layer cover (221) is disposed in a moveable cover (76); the width of the moveable cover (76) equals to the width between the front and rear sides of the transversal layer cover (221) and the length of the moveable cover equals to the length between the left and right desk legs; the inward recess at the opposite sides of the left and right moveable cover (76) is formed by vertical plates, upper/lower strips and front/rear baffles; the front of the recess is disposed with a convex plate (78) at the left and right legs; the convex plate is then equipped with a spring; between the left and right desk legs, the rear of the recess is sheathed with the desk footrest (20) whose width equals to the length of the desk leg; the shaft passes through the aperture, the spring and the convex plate (78) that are in the recess of the desk footrest (20) to fix the desk footrest to the center of the front and rear baffles of the recess; the upper and lower portions of the front section of the recess are attached by the connecting plate (26) as a whole; because the desk footrest (20) is extendable and the desk can move close to the chair, the leg cover opening (85) is not required; the middle of the two desk bases (9) and the connecting plate (26) in the middle of the desk bases (9) are disposed with a lock (79); an aperture (232) in the middle of the left and right sides of the long-strip plate (82) of the lock (79) is moveably connected with the corresponding portion of the connecting plate (26) and the aperture (232) is used as the centre of circle to the bottom of the strips (23) at the middle of the front and rear desk legs as an arc edge (81); from the aperture (232) on a long-strip plate (82) to one side of the chair at one end of the arc edge (81) is connected with an acute angle plate that is shorter from the aperture (232) to the arc edge (81); the other end of the acute angel plate having the same length as the acute angle plate has a side edge facing downwards of 90°; and the upper portion of the chair legs are further equipped with the longitudinal layer cover (22) and the flat square (182).
 12. The bionic and posture-correcting desk and chair of claim 9, wherein for the posture-correcting device and the mechanism for fixing the posture-correcting device, a height-fixed desk and chair is provided with a maximum height and space (38); one or more footrests are disposed at the place where the feet are placed; the point from the lower end of the desk and chair to the maximum height is moveably connected with the chair footrest (201); the width of the chair footrest (201) is the width of the desk and chair and the length of the chair footrest is the maximum length when the desk and chair are separate; the footrest can move in the support plate (60); the footrest and the support plate (60) can be adjusted up and down; the chair surface fit with the layer covers on the chair legs; the footrest seat (58) in the section from one end to the maximum height of the chair is moveably connected with the chair footrest (201), whose the end close to the chair is lower and the end far from the chair is a little higher; the width of the chair footrest (201) equals to the width of the desk and chair and the length of the chair footrest equals to the maximum length when the desk and chair are separate; at that point, the footrest on the desk support plate (60) or the butt plate projected from two sides of the chair footrest (201) is moveable along the connecting bracket (71), or the chair footrest (201) is against the ground; the resistance point of the lever provides resilient support or is the support pillar; the support pillar supports the resilient footrest; and the footrest seat (58) and the support plate (60) are adjustable up and down.
 13. The bionic and posture-correcting desk and chair of claim 1, wherein the footrest or the support plate (60) is disposed with the leg cover opening (85) or the leg cover hole, or under the footrest or the support plate (60) is disposed with a leg space (87); the width of the leg cover opening (85) of the desk footrest (20) close to the chair is a little more than the width of the left and right chair front legs or equal to the width between the left and right front legs or the chair box (12); the front and rear of the desk come close to the maximum of one or two vertical rectangle or a transversal rectangular opening; the leg cover opening (85) fits with the leg cover hole; the leg cover hole which is at the front (or slightly at the rear side) of the desk footrest (20) fits with the leg cover opening (85) at the rear of the desk footrest; the width of the leg cover hole equals to the width of the leg cover opening (85) and the length is slightly longer than the length between the front and rear of the front leg; the shape is one or two square, rectangle or circle or a transversal rectangular hole or opening; the leg space ((87) is at the bottom of the desk footrest (20); the height of the leg space is slightly higher than or as high as the chair base (9) and the width is slightly wider than the chair base (9) or includes the two chair bases (9); the length of the leg space is in the space of two vertical cuboids or a big transversal flat cuboid of the desk footrest (20) when the chair base (9) is sheathed into the desk footrest (20) to the limit; and the leg cover opening (85) and the leg cover hole on the support plate (60) or the leg space (87) under the support plate are similar to the desk footrest (20).
 14. The bionic and posture-correcting desk and chair of claim 1, wherein the desk is disposed with the desk backrest (21); the desk backrest (21) includes a bracket body at the rear of the desk where a mounting bracket (90) is disposed; when a user sits on the chair behind the desk, the frame (from the chest and abdomen to the desk edge, from the chin to the lower part of the abdomen and above the thighs) is disposed with an adjustable adjustment element, which allows the user to maintain the correct “forward sitting position” and “backward sitting position” or a position in between; the bracket body includes at least one adjustable tubular pile (147) and a pectoral/ventral plate (178); the pectoral/ventral plate (178) is moveably connected with an upper adjustable plate (98); inside the adjustable tubular pile (147) is sheathed with a chin adjustment element, which is used to adjust the height of the chinrest (177); the mounting bracket (21) is on the desk or on the base plate (91) at the upper end of the desk box; the lower end of the single-column lower adjustable pillar, similar to the desk backrest (21), extends to the lower part of the abdomen and the bottom of the desk box (desk box baseplate from the chest to the desk edge; the upper part of the thighs is disposed with the pectoral/ventral plate (178), which is used to fix the lower end of the lower adjustable pillar to the mounting bracket (90); in the invention, the fixed connection is changed to the moveable connection; the sternal plate and the ventral plate of the mounting bracket (90) is moveably connected with the upper adjustable plate (98), which is inserted in a transversal gap (67) of the adjustable plate cover or the adjustable cover of the mounting plate (90); the pectoral/ventral plate (178) is indirectly moveably connected with a chair back (17) to make the desk and chair form a whole part; the lower end of the pectoral/ventral plate (178) is connected with an adjustable plate (99), which is directly or indirectly moveably connected with an adjustable baseplate (89), a desktop lifting mechanism or a bookrack lifting mechanism; and the bracket body is disposed with a ventral plate adjustment mechanism and a bracket folding mechanism.
 15. The bionic and posture-correcting desk and chair of claim 1, wherein the desktop lifting mechanism is one or two pumpkin-seed-shaped lifting plates (102) and placed on the desk box baseplate (13); two sides of the desktop lifting mechanism are fixed with vertical clamp plate (101); the rear upper portion of the vertical clamp plate (101) is moveably connected with the corresponding part of the lifting plate (102); the rear top end of the lifting plate (102) is moveably connected with the front end of a secondary connecting plate (103); the rear of the secondary connecting plate (103) is placed on a raised edge (104) at the rear edge of the adjustable baseplate (89) and the raised edge extends out of the adjustable baseplate; the lower adjustable plate (99) that is moveably connected with the lower end of the desk backrest (21) is moveably connected with a step (105) and a flat plate (106) on the secondary connecting plate (103) as well as a magnet (57) that is disposed in the middle of the raised edge (104) of the adjustable baseplate (89); the front ends of the left and right lifting plates (102) are connected with 1-2 connecting plate (26); the bottom of the desk box baseplate (13) is reversely disposed with a spring adjustment element; a reversed hanger plate (107) of the spring adjustment element is in the middle of the left and right front ends; the reversed hanger plate is moveably connected with the front end of a longitudinal plate (261) and 1-2 columns (83) stand on the rear front end or slightly inner position of the reversed hanger plate; the spring (35) on the column (83) supports the desk box baseplate (13) and is against the longitudinal plate (261); the column (83) passes through the hole (32) on the desk box baseplate (13); and the upper end of the column is sheathed with a hanger plate whose diameter is larger than that of the column (83) and is moveably hanged on the desk box baseplate (13) to be parallel with the upper portion of the adjustable baseplate (89); alternatively the longitudinal plate (261) is placed on the reversed hook at the bottom of the column; at the corresponding place of the secondary connecting plate (103) is disposed with an aperture to fit with the column (83).
 16. The bionic and posture-correcting desk and chair of claim 1, wherein the desk equipped with the desktop lifting mechanism is moveably connected with a bookrack; a bookrack seat (110) at the front end of the lifting plate (102) is moveably connected with 1-2 frame tubes (111) in the transversal direction; the upper end of the frame tube (111) vertically passes through and extends over the top of the desktop; the bookrack (109) is composed of the book placing board (115) and 1-2 support tubes (112) that are moveably connected at the rear of the bookrack; the book placing board (115) is disposed with a book holding groove (116) and the lower end of the book placing board is connected with a book baffle; the support tube (112) of the bookrack (109) and the frame tube (111) are moveably sheathed together; and the left and right sides of the book placing board (115) indirectly attracts with the opened book by magnet.
 17. The bionic and posture-correcting desk and chair of claim 1, wherein the desktop is disposed with the desktop lifting mechanism, which is at the upper and lower sides in the transversal direction of the length of a lifting adjustment plate (126); one side is parallel and the other side is inclined; on the lifting adjustment plate (126) is disposed with the adjustable slot (94), which is parallel with the parallel edge of the lifting adjustment plate (126); the lifting adjustment plate (126) is fixed on the desk box side plate (16) by bolts (34) via the adjustable slot (94); furthermore, the adjustable slot (94) parallel to the lifting adjustment plate (126) can be transversally disposed at the corresponding position of the desk box side plate (16); in the middle of the transversal adjustable slot (94) is disposed with a vertical slot; and the lifting adjustment plate (126) is sheathed on the desk box side plate (16) via the adjustable slot (94).
 18. The bionic and posture-correcting desk and chair of claim 1, wherein the chair is on the ground; the front of the desk is disposed with the wheel (11) and the rear of the desk is disposed with the desk base-top (10); alternatively, the front and rear of the desk are both disposed with the wheels (11), or the desk is fixed on the ground, or the front and rear of the chair are both disposed with the wheels (11); the chair is fixed on the ground at the inner side of the two parallel tracks (30) or close to the inner side of the two tracks (30) or on the tracks (30); the desk is on the two tracks (30) or close to the outer side of the tracks (30) or on the ground at the outer side of the tracks (30); the front of the desk is disposed with the wheel (11) and the rear of the desk is disposed with the desk base-top (10), or the front and rear of the desk are both disposed with the wheels (11), or the desk is fixed on the ground at the outer side of the two parallel tracks (30) or close to the outer side of the tracks (30) or on the tracks (30); the chair is on the two tracks (30) or close to the inner side of the track (30) or on the ground at the inner side of the track (30); the chair is disposed on the track (30) of a desk/chair holder (130) or of a double-layer desk/chair holder (131) or disposed on the connecting plate (26); the desk is disposed on the track (30) at the front of the chair, the front of the desk is disposed with the wheel (11), and the rear of the desk is disposed with the desk base-top (10) or both the front and rear of the desk are disposed with the wheels (11); alternatively, the desk is disposed on the track (30) of the desk/chair holder (130) or of the double-layer desk/chair holder (131) or disposed on the connecting plate (26); the chair is disposed on the track (30) at the rear of the desk and both the front and rear of the chair are disposed with the wheels (11); the desk/chair holder (130) is a frame composed of one or more pairs of longitudinal tracks (30) and two or more transversal connecting plates (26), or the double-layer desk/chair holder (131) is formed by connecting the upper and lower frames; under the desk/chair holder (130) and the double-layer desk/chair holder (131) are disposed with support legs (136) or the wheels (11); the desk/chair holder (130) and the double-layer desk/chair holder (131) can be disposed with one or more sets or one or more rows of desks and chairs in the longitudinal and transversal directions, respectively; the desks and chairs are not against one another; the wheels (11) at the front end of the desk base (9) are parallel with the desk base (9) and the ground; the front end of the desk base (9) is in the shape of an arc; and the lower sections of the chair legs can be omitted; it is only required to mount the upper sections of the chair legs on the desk/chair holder (130), or the inner sides of the tracks (30) and the connecting plate (26).
 19. The bionic and posture-correcting desk and chair of claim 1, wherein the chair back support (18) is disposed with the chair back adjustment mechanism.
 20. The bionic and posture-correcting desk and chair of claim 19, wherein for the chair back adjustment mechanism, the chair back (17) is moveably connected with the sternal/ventral plate (178) of the desk backrest (21) in an indirect way; the chair back (17) is moveably connected with the upper section of the chair back support (18) by bolts (34) via the positional adjustment holes 32 on the chair back support (18); the chair back (17) is disposed with a pillow backrest (135); the pillow backrest (135) is covered by a pillow (137) and provides support for the waist; the lower end of the pillow backrest (135) can be inserted in the chair back support (18) or a storage tube (138) at the rear of the chair legs; and a chair box (12) is added under the chair.
 21. The bionic and posture-correcting desk and chair of claim 1, wherein on the chair back support (18) is disposed with the chair back support adjustment mechanism.
 22. The bionic and posture-correcting desk and chair of claim 21, wherein the chair back support adjustment mechanism divides the left and right chair back supports (18) into upper and lower chair back supports; the upper chair back support is covered in the lower chair back support; the relative inner sides of the upper ends of the two upper chair back supports are moveably connected with the chair back (17); the lower sections of the two upper chair back supports are fixed with a resilient adjustment pin; the resilient adjustment pin is a resilient strip (piece) and is in a bended shape (or the circular bended shape); the end of the bended strip is disposed with 1-2 projected pins, passing through the aperture on the inner wall of the upper chair back support and fit with the positional adjustment holes of the lower chair back support; and the two ends of the chair back (17) are moveably connected with the upper chair back support and can be adjusted up and down in the lower chair back support. 